A hydrofunctionalization reaction is the addition of hydrogen and another univalent fragment (X) across a carbon-carbon or carbon-heteroatom multiple bond.
[1] Often, the term hydrofunctionalization without modifier refers specifically to the use of the covalent hydride (H-X) as the source of hydrogen and X for this transformation.
If other reagents are used to achieve the net addition of hydrogen and X across a multiple bond, the process may be referred to as a formal hydrofunctionalization.
For terminal olefins (or acetylenes), the regioselectivity of the process can be described as Markovnikov (addition of X at the substituted end) or anti-Markovnikov (addition of X at the unsubstituted end).
Catalysts are frequently employed to control the chemo-, regio-, and stereoselectivity of hydrofunctionalization reactions.